A rotatable connector device which is mountable on a vehicle such as an automobile or the like includes a stator fixed to a vehicle body and a rotator attached to a steering wheel. The stator and the rotator are coaxially attached to each other so as to be rotatable with respect to each other. The rotatable connector device further includes flat cables located in an accommodation space formed by the stator and the rotator.
The flat cables electrically connect electric components such as a horn module, an airbag module, an audio control module and the like provided on the side of the steering wheel and a power supply on the side of the vehicle body to each other.
Patent Document 1 filed by the present applicant, for example, proposes a rotatable connector device including a retainer, located on a bottom surface of the accommodation space, for guiding the flat cables to rotate around an axis of the steering wheel.
Such a retainer includes a plurality of rotatable rollers and a guide unit (corresponding to a “guide wall” in Patent Document 1) projecting in the vicinity of one of the rotatable rollers. The retainer assists the flat cables in being rotated in the accommodation space in a winding or rewinding direction, so that the rotatable connector device can follow the steering operation to rotate smoothly.
This will be described in more detail. As shown in FIG. 11, flat cables C include, in the accommodation space S, an outside wound part Co wound along an inner circumferential surface of an outer cylindrical section 32 of the stator 30, a reversed part Cr which is wound along one of the plurality of rotatable rollers 45 axially supported by a retainer 40 and turned around in a U shape, and an inside wound part Ci wound along an outer circumferential surface of an inner cylindrical section 22 of the rotator 20.
In the rotatable connector device having such a structure, when the rotator 20 is rotated clockwise (X direction in FIG. 11), the reversed part Cr of the flat cables C is pressed on a guide unit 48, and the pressing force causes the retainer 40 to rotate in the clockwise direction. When the rotor is rotated in a counterclockwise direction (Y direction in FIG. 11), the reversed part Cr of the flat cables C is pulled counterclockwise along the rotatable roller 45, and thus the retainer 40 is rotated counterclockwise.
In such a structure, when the rotator 20 is rotated clockwise, the reversed part Cr of the flat cables C always receives a reaction force from the guide unit 48. Therefore, a laminate structure of the flat cables C on the guide unit 48 side may be abraded by the repeated rotation of the rotator 20, which may cause a fault.